Patent DE-102007034423-B3 (DE)
Title: Welding tongs for resistance spot welding, comprise two tong limbs relatively displaced to each other and having welding electrode at its first end and first and second tong arm thigh that are connected with one another at second end
Inventor: KRASKA MARTIN
IPC: B23K11/28
Filed: 2007-07-20
Granted: 2008-12-24
Abstract: The welding tongs for resistance spot welding, comprise two tong limbs (1) relatively displaced to each other and having a welding electrode at its first end and a first and a second tong arm thigh (2, 3) that are connected with one another at a second end (5) in rigid and right-angled manner. The welding electrodes are disposed to set a locally pre-determined welding point by a driving power (P) charged on the opposite second end of each welding tongs arm. The each tong limb is formed by a carrier with cross section, which is changeable over its longitudinal extending. The welding tongs for resistance spot welding comprise two tong limbs (1) relatively displaced to each other and having a welding electrode at its first end and a first and a second tong arm thigh (2, 3) that are connected with one another at a second end (5) in rigid and right-angled manner. The welding electrodes are disposed to set a locally pre-determined welding point by a driving power (P) charged on the opposite second end of each welding tongs arm. The each tong limb is formed by a carrier with cross section, which is changeable over its longitudinal extending and converts a shear force operating for the longitudinal direction of the carrier in a cross section. The parameters of the tong limb are optimized so that when welding a displacement (u=0.01 mm) of the caps of the welding electrodes in reference on the pre-determined is zero. The longitudinal sections of the welding tong limb are trapezoidal. The height dimension (h1) of the trapezoidal section (D) of the longitudinal section of the tong limb at its first end is smaller than the height dimension (h3) of the trapezoidal section (D) at its second end. A bar (8) of the carrier extends itself on the second end over the length (a) of the tong limb. A recess extending itself over the remaining length (D) of the tong limb to the welding electrode is formed between an upper and lower belt (10) of the carrier. The bar of the carrier is arranged in its longitudinal direction in the distance and has holes and recesses extending itself over the height of the bar. The first welding tong arm thigh is formed as carrier. The parameters of the tong limb are optimized by: the first tong arm thigh having a length of 600 mm, height dimension (h1) of 37.50 mm, bar strength (s) of 5 mm, longitudinal sections (C) of 200 mm measured at second end, height dimension (h3) of 50 mm and longitudinal sections (d) of the continuous section of 400 mm; the second welding tong arm thigh having a length of b = 250 mm, height dimension (h2) of 50.00 mm, cross-section area (Qb) of the lower belt of 40 mmx 10 mm and cross-section area of 40 mmx 40 mm; and moment forcing of the tong limb of M1+M3=M2 and/or M1-3=0, where M1=tong clamp force (5 kN)x length (a=600 mm), M2=force P1 (60 kN)x length (b=250 mm) and M3=force P2 (60 kN)x length (b-h2 200 mm).